Interleukin-1 in Stroke: From Bench to Bedside

Stroke as a career option for neurologists

Stroke is one of the most common acute neurological disorders and a leading cause of disability worldwide. Evidence-based treatments over the last two decades have driven a revolution in the clinical management and design of stroke services. We need a highly skilled, multidisciplinary workforce that includes neurologists as core members to deliver modern stroke care. In the UK, the dedicated subspecialty training programme for stroke medicine has recently been integrated into the neurology curriculum. All neurologists will be trained to contribute to each aspect of the stroke care pathway. We discuss how training in stroke medicine is evolving for neurologists and the opportunities and challenges around practising stroke medicine in the UK and beyond.

Role of microglia in stroke

Microglia play key roles in the post-ischemic inflammatory response and damaged tissue removal reacting rapidly to the disturbances caused by ischemia and working to restore the lost homeostasis. However, the modified environment, encompassing ionic imbalances, disruption of crucial neuron-microglia interactions, spreading depolarization, and generation of danger signals from necrotic neurons, induce morphological and phenotypic shifts in microglia. This leads them to adopt a proinflammatory profile and heighten their phagocytic activity. From day three post-ischemia, macrophages infiltrate the necrotic core while microglia amass at the periphery. Further, inflammation prompts a metabolic shift favoring glycolysis, the pentose-phosphate shunt, and lipid synthesis. These shifts, combined with phagocytic lipid intake, drive lipid droplet biogenesis, fuel anabolism, and enable microglia proliferation. Proliferating microglia release trophic factors contributing to protection and repair. However, some microglia accumulate lipids persistently and transform into dysfunctional and potentially harmful foam cells. Studies also showed microglia that either display impaired apoptotic cell clearance, or eliminate synapses, viable neurons, or endothelial cells. Yet, it will be essential to elucidate the viability of engulfed cells, the features of the local environment, the extent of tissue damage, and the temporal sequence. Ischemia provides a rich variety of region- and injury-dependent stimuli for microglia, evolving with time and generating distinct microglia phenotypes including those exhibiting proinflammatory or dysfunctional traits and others showing pro-repair features. Accurate profiling of microglia phenotypes, alongside with a more precise understanding of the associated post-ischemic tissue conditions, is a necessary step to serve as the potential foundation for focused interventions in human stroke.

Peripheral inflammatory response in people after acute ischaemic stroke and isolated spontaneous cervical artery dissection

The systemic inflammatory response following acute ischaemic stroke remains incompletely understood. We characterised the circulating inflammatory profile in 173 acute ischaemic stroke patients by measuring 65 cytokines and chemokines in plasma. Participants were grouped based on their inflammatory response, determined by high-sensitivity C-reactive protein levels in the acute phase. We compared stroke patients' profiles with 42 people experiencing spontaneous cervical artery dissection without stroke. Furthermore, variations in cytokine levels among stroke aetiologies were analysed. Follow-up samples were collected in a subgroup of ischaemic stroke patients at three and twelve months. Ischaemic stroke patients had elevated plasma levels of HGF and SDF-1α, and lower IL-4 levels, compared to spontaneous cervical artery dissection patients without stroke. Aetiology-subgroup analysis revealed reduced levels of nine cytokines/chemokines (HGF, SDF-1α, IL-2R, CD30, TNF-RII, IL-16, MIF, APRIL, SCF), and elevated levels of IL-4 and MIP-1β, in spontaneous cervical artery dissection (with or without ischaemic stroke as levels were comparable between both groups) compared to other aetiologies. The majority of cytokine/chemokine levels remained stable across the study period. Our research indicates that stroke due to large artery atherosclerosis, cardioembolism, and small vessel occlusion triggers a stronger inflammatory response than spontaneous cervical artery dissection.

IL-1β disrupts the initiation of blood-brain barrier development by inhibiting endothelial Wnt/β-catenin signaling

During neuroinflammation, the proinflammatory cytokine interleukin-1β (IL-1β) impacts blood-brain barrier (BBB) function by disrupting brain endothelial tight junctions, promoting vascular permeability, and increasing transmigration of immune cells. Here, we examined the effects of Il-1β on the in vivo initiation of BBB development. We generated doxycycline-inducible transgenic zebrafish to secrete Il-1β in the CNS. To validate the utility of our model, we showed Il-1β dose-dependent mortality, recruitment of neutrophils, and expansion of microglia. Using live imaging, we discovered that Il-1β causes a significant reduction in CNS angiogenesis and barriergenesis. To demonstrate specificity, we rescued the Il-1β induced phenotypes by targeting the zebrafish il1r1 gene using CRISPR-Cas9. Mechanistically, we determined that Il-1β disrupts the initiation of BBB development by decreasing Wnt/β-catenin transcriptional activation in brain endothelial cells. Given that several neurodevelopmental disorders are associated with inflammation, our findings support further investigation into the connections between proinflammatory cytokines, neuroinflammation, and neurovascular development.

Microglia-neuron-vascular interactions in ischemia

Cerebral ischemia is a devastating condition that results in impaired blood flow in the brain leading to acute brain injury. As the most common form of stroke, occlusion of cerebral arteries leads to a characteristic sequence of pathophysiological changes in the brain tissue. The mechanisms involved, and comorbidities that determine outcome after an ischemic event appear to be highly heterogeneous. On their own, the processes leading to neuronal injury in the absence of sufficient blood supply to meet the metabolic demand of the cells are complex and manifest at different temporal and spatial scales. While the contribution of non-neuronal cells to stroke pathophysiology is increasingly recognized, recent data show that microglia, the main immune cells of the central nervous system parenchyma, play previously unrecognized roles in basic physiological processes beyond their inflammatory functions, which markedly change during ischemic conditions. In this review, we aim to discuss some of the known microglia-neuron-vascular interactions assumed to contribute to the acute and delayed pathologies after cerebral ischemia. Because the mechanisms of neuronal injury have been extensively discussed in several excellent previous reviews, here we focus on some recently explored pathways that may directly or indirectly shape neuronal injury through microglia-related actions. These discoveries suggest that modulating gliovascular processes in different forms of stroke and other neurological disorders might have presently unexplored therapeutic potential in combination with neuroprotective and flow restoration strategies.

Genetics of ischemic stroke functional outcome

Ischemic stroke, which accounts for 87% of cerebrovascular accidents, is responsible for massive global burden both in terms of economic cost and personal hardship. Many stroke survivors face long-term disability-a phenotype associated with an increasing number of genetic variants. While clinical variables such as stroke severity greatly impact recovery, genetic polymorphisms linked to functional outcome may offer physicians a unique opportunity to deliver personalized care based on their patient's genetic makeup, leading to improved outcomes. A comprehensive catalogue of the variants at play is required for such an approach. In this review, we compile and describe the polymorphisms associated with outcome scores such as modified Rankin Scale and Barthel Index. Our search identified 74 known genetic polymorphisms spread across 48 features associated with various poststroke disability metrics. The known variants span diverse biological systems and are related to inflammation, vascular homeostasis, growth factors, metabolism, the p53 regulatory pathway, and mitochondrial variation. Understanding how these variants influence functional outcome may be helpful in maximizing poststroke recovery.

Social isolation initiated post-weaning augments ischemic brain injury by promoting pro-inflammatory responses

Social isolation is associated with poor stroke outcome, but the underlying molecular mechanisms were largely unknown. In male Balb/C mice exposed to transient middle cerebral artery occlusion (MCAo), we examined the effects of social isolation initiated post-weaning on ischemic injury, cytokine/chemokine responses and cell signaling using a broad panel of techniques that involved immunocytochemistry, cytokine/chemokine array and Western blots. Social isolation initiated post-weaning elevated infarct size, brain edema and neuronal injury in the ischemic brain tissue 3 days after MCAo, and increased microglia/ macrophage and leukocyte accumulation. In line with the increased immune cell recruitment, levels of several proinflammatory cytokines (e.g., IL-1α, IL-1β, IL-13, IL-17, TNF-α, IFN-γ), chemokines (e.g., CCL3, CCL4, CCL12, CXCL2, CXCL9, CXCL12) and adhesion molecules (i.e., ICAM-1) were increased in the ischemic brain tissue of socially isolated compared with paired housing mice, whereas levels of selected cytokines (IL-5, IL-6, IL-16) and colony-stimulating factors (G-CSF, GM-CSF) were reduced. The activity of the transcription factor nuclear factor-ĸB (NF-ĸB), which promotes cell injury via pro-inflammatory responses, was increased by social isolation, whereas that of nuclear factor erythroid related factor-2 (Nrf-2), which mediates anti-oxidative responses under oxidative stress conditions, was reduced. Our study shows that social isolation profoundly alters post-ischemic cell signaling in a way promoting pro-inflammatory responses. Our results highlight the importance of social support in preventing deleterious health effects of social isolation.

The case for neuregulin-1 as a clinical treatment for stroke

Ischemic stroke is the leading cause of serious long-term disability and the 5th leading cause of death in the United States. Revascularization of the occluded cerebral artery, either by thrombolysis or endovascular thrombectomy, is the only effective, clinically-approved stroke therapy. Several potentially neuroprotective agents, including glutamate antagonists, anti-inflammatory compounds and free radical scavenging agents were shown to be effective neuroprotectants in preclinical animal models of brain ischemia. However, these compounds did not demonstrate efficacy in clinical trials with human patients following stroke. Proposed reasons for the translational failure include an insufficient understanding on the cellular and molecular pathophysiology of ischemic stroke, lack of alignment between preclinical and clinical studies and inappropriate design of clinical trials based on the preclinical findings. Therefore, novel neuroprotective treatments must be developed based on a clearer understanding of the complex spatiotemporal mechanisms of ischemic stroke and with proper clinical trial design based on the preclinical findings from specific animal models of stroke. We and others have demonstrated the clinical potential for neuregulin-1 (NRG-1) in preclinical stroke studies. NRG-1 significantly reduced ischemia-induced neuronal death, neuroinflammation and oxidative stress in rodent stroke models with a therapeutic window of >13 h. Clinically, NRG-1 was shown to be safe in human patients and improved cardiac function in multisite phase II studies for heart failure. This review summarizes previous stroke clinical candidates and provides evidence that NRG-1 represents a novel, safe, neuroprotective strategy that has potential therapeutic value in treating individuals after acute ischemic stroke.

Selective deletion of interleukin-1 alpha in microglia regulates neuronal responses and neurorepair processes after experimental ischemic stroke

Inflammation is a key contributor to stroke pathogenesis and drives exacerbated brain damage leading to poor outcome. Interleukin-1 (IL-1) is an important regulator of post-stroke inflammation, and blocking its actions is beneficial in pre-clinical stroke models and safe in the clinical setting. IL-1α and IL-1β are the two major IL-1 type 1 receptor (IL-1R1) agonists from the IL-1 family. The distinct roles of both isoforms, and particularly that of IL-1α, remain largely unknown. Here we show that IL-1α and IL-1β have different spatio-temporal expression profiles in the brain after experimental stroke, with early microglial IL-1α expression (4 h) and delayed IL-1β expression in infiltrated neutrophils and a small microglial subset (24-72 h). We examined the specific contribution of microglial-derived IL-1α in experimental permanent and transient ischemic stroke through cell-specific tamoxifen-inducible Cre-loxP-mediated recombination. Microglial IL-1α deletion did not influence acute brain damage, cerebral blood flow, IL-1β expression, neutrophil infiltration, microglial nor endothelial activation after ischemic stroke. However, microglial IL-1α knock out (KO) mice showed reduced peri-infarct vessel density and reactive astrogliosis at 14 days post-stroke, alongside a worse functional recovery. RNA sequencing analysis and subsequent pathway analysis on ipsilateral/contralateral cortex 4 h after stroke revealed a downregulation of the neuronal CREB signaling pathway in microglial IL-1α KO compared to WT mice. Our study identifies for the first time a critical role for microglial IL-1α on neuronal activity, neurorepair and functional recovery after stroke, highlighting the importance of targeting specific IL-1 mechanisms in brain injury to develop more effective therapies.

Anakinra in cerebral haemorrhage to target secondary injury resulting from neuroinflammation (ACTION): Study protocol of a phase II randomised clinical trial

BACKGROUND

Inflammation plays a vital role in the development of secondary brain injury after spontaneous intracerebral haemorrhage (ICH). Interleukin-1 beta is an early pro-inflammatory cytokine and a potential therapeutic target.

AIM

To determine the effect of treatment with recombinant human interleukin-1 receptor antagonist anakinra on perihematomal oedema (PHO) formation in patients with spontaneous ICH compared to standard medical management, and investigate whether this effect is dose-dependent.

METHODS

ACTION is a phase-II, prospective, randomised, three-armed (1:1:1) trial with open-label treatment and blinded end-point assessment (PROBE) at three hospitals in The Netherlands. We will include 75 patients with a supratentorial spontaneous ICH admitted within 8 h after symptom onset. Participants will receive anakinra in a high dose (loading dose 500 mg intravenously, followed by infusion with 2 mg/kg/h over 72 h; n = 25) or in a low dose (loading dose 100 mg subcutaneously, followed by 100 mg subcutaneous twice daily for 72 h; n = 25), plus standard care. The control group (n = 25) will receive standard medical management.

OUTCOMES

Primary outcome is PHO, measured as oedema extension distance on MRI at day 7 ± 1. Secondary outcomes include the safety profile of anakinra, the effect of anakinra on serum inflammation markers, MRI measures of blood brain barrier integrity, and functional outcome at 90 ± 7 days.

DISCUSSION

The ACTION trial will provide insight into whether targeting interleukin-1 beta in the early time window after ICH onset could ameliorate secondary brain injury. This may contribute to the development of new treatment options to improve clinical outcome after ICH.

IL-1β disrupts blood-brain barrier development by inhibiting endothelial Wnt/β-catenin signaling

During neuroinflammation, the proinflammatory cytokine Interleukin-1β (IL-1β) impacts blood-brain barrier (BBB) function by disrupting brain endothelial tight junctions, promoting vascular permeability, and increasing transmigration of immune cells. Here, we examined the effects of Il-1β on the in vivo development of the BBB. We generated a doxycycline-inducible transgenic zebrafish model that drives secretion of Il-1β in the CNS. To validate the utility of our model, we showed Il-1β dose-dependent mortality, recruitment of neutrophils, and expansion of microglia. Using live imaging, we discovered that Il-1β causes a significant reduction in CNS angiogenesis and barriergenesis. To demonstrate specificity, we rescued the Il-1β induced phenotypes by targeting the zebrafish il1r1 gene using CRISPR/Cas9. Mechanistically, we determined that Il-1β disrupts BBB development by decreasing Wnt/β-catenin transcriptional activation in brain endothelial cells. Given that several neurodevelopmental disorders are associated with inflammation, our findings support further investigation into the connections between proinflammatory cytokines, neuroinflammation, and neurovascular development.

Phase II randomised, placebo-controlled, clinical trial of interleukin-1 receptor antagonist in intracerebral haemorrhage: BLOcking the Cytokine IL-1 in ICH (BLOC-ICH)

PURPOSE

Recombinant human interleukin-1 receptor antagonist (anakinra) is an anti-inflammatory with efficacy in animal models of stroke. We tested the effect of anakinra on perihaematomal oedema in acute intracerebral haemorrhage (ICH) and explored effects on inflammatory markers.

METHODS

We conducted a multicentre, randomised, double-blind, placebo-controlled trial in patients with acute, spontaneous, supratentorial ICH between May 2019 and February 2021. Patients were randomised to 100 mg subcutaneous anakinra within 8 h of onset, followed by five, 12-hourly, 100 mg subcutaneous injections, or matched placebo. Primary outcome was oedema extension distance (OED) on a 72 h CT scan. Secondary outcomes included plasma C-reactive protein (CRP) and interleukin-6 (IL-6).

FINDINGS

25 patients (target = 80) were recruited, 14 randomised to anakinra, 11 to placebo. Mean age was 67 and 52% were male. The anakinra group had higher median baseline ICH volume (12.6 ml, interquartile range[IQR]:4.8-17.9) versus placebo (5.5 ml, IQR:2.1-10.9). Adjusting for baseline, 72 h OED was not significantly different between groups (mean difference OED anakinra vs placebo -0.05 cm, 95% confidence interval [CI]: -0.17-0.06, p = 0.336). There was no significant difference in area-under-the-curve to Day 4 for IL-6 and CRP, but a post-hoc analysis demonstrated IL-6 was 56% (95% CI: 2%-80%) lower at Day 2 with anakinra. There were 10 and 2 serious adverse events in anakinra and placebo groups, respectively, none attributed to anakinra.

CONCLUSION

We describe feasibility for delivering anakinra in acute ICH and provide preliminary safety data. We lacked power to test for effects on oedema thus further trials will be required.

C-reactive protein levels are associated with early cardiac complications or death in patients with acute ischemic stroke: a propensity-matched analysis of a global federated health from the TriNetX network

The role of inflammation in predicting early cardiac complications among stroke patients is unclear. Electronic medical records from TriNetX, a global federated health research network, were used for this retrospective analysis. Patients with ischemic stroke and C-Reactive Protein (CRP) levels measured within 24 h post-stroke were categorized into three groups: (i) < 1 mg/L, (ii)1-3 mg/L and (iii) > 3 mg/L. The primary outcome was a composite outcome of cardiac complications (heart failure (HF), ischemic heart disease, atrial fibrillation (AF), ventricular arrhythmias and Takotsubo cardiomyopathy) or death at 30 days from the index event. Cox-regression analyses were used to produce hazard ratios (HRs) and 95% confidence intervals (CI) following 1:1 propensity score matching (PSM). Of the 104,741 patients enrolled, 51% were female and the mean age was 66 ± 16 years. After PSM, a new cardiac complication or death within 30 days occurred in 5624 (33.1%) patients with CRP > 3 mg/L, in 4243 (25.6%) patients with CRP 1-3 mg/L and in 3891 (23.5%) patients with CRP < 1 mg/L. Patients with CRP levels of 1-3 mg/L and > 3 mg/L had higher risk of the composite outcome (HR 1.10, 95%CI 1.05-1.52; HR 1.51, 95%CI 1.45-1.58), death (HR 1.43, 95%CI 1.24-1.64; HR 3.50, 95%CI 3.01-3.96), HF (HR 1.08, 95%CI 1.01-1.16; HR 1.51, 95%CI 1.41-1.61), AF (HR 1.10, 95% CI:1.02-1.18; HR 1.42, 95%CI 1.33-1.52) and ventricular arrhythmias (HR 1.25, 95%CI 1.02-1.52; HR 1.67, 95% CI 1.38-2.01) compared to those with CRP < 1 mg/L. Ischemic heart disease were more common among patients with CRP levels > 3 mg/L compared to those with CRP < 1 mg/L (HR:1.33, 95% CI:1.26-1.40), while no association with Takotsubo cardiomyopathy was found in all the analyses. CRP levels within the first 24 h of an ischemic stroke predict 30-day cardiac complications or death.

Effect of High-dose Vitamin D on IL-1β Blood Level in Patients with Moderate Stroke: A Randomized Clinical Trial

Background

Vitamin D has neuroprotective and anti-inflammatory effects in stroke patients, but its effect on pro-inflammatory and inflammatory cytokines, especially IL-1, has been investigated in a few trials.

Objectives

This study aimed to determine the effect of prescribing a high dose of vitamin D on the anti-inflammatory parameters, short-term and long-term prognosis of patients with ischemic stroke.

Methods

This randomized clinical trial was performed on 42 patients randomly divided into two equal groups of 21 in Imam Hussein Hospital. The patients were allocated through block randomization methods to receive 300,000 units of vitamin D (intramuscularly) or not receive it as a control group. Age, gender, and clinical and laboratory information were recorded. The stroke severity was calculated according to the National Institute of Health Stroke Scale (NIHSS) at the beginning of hospitalization and upon hospital discharge. The 3-month prognosis of the patients was recorded according to the Barthel criteria three months after the stroke. Vitamin D3 levels were recorded before and after injection, while the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were assessed on the first day and for 7 consecutive days after hospitalization. All statistical analyses were performed using STATA version 14. A P-value < 0.05 was considered significant.

Results

The mean age of the patients was 61.45 ± 4.74 years. There were 18 female (42.86%) and 24 male patients (57.14%). In the vitamin D group, the mean IL-1 decreased compared to before the intervention (-23.60 ± 103.83), but this decrease was not statistically significant (P = 0.070). In addition, the changes in IL-1 after the intervention were statistically different between the two groups (mean difference of -23.60 ± 103.83 in the vitamin D group vs. 15.96 ± 9.64 in the control group). The mean IL-6 decreased in both groups after the intervention compared to before, although these changes were not statistically significant (P > 0.05). In the group receiving vitamin D compared to the control group, the mean NLR decreased by about 2 units, the PLR decreased by about 10 units, and the NIHSS score decreased by about one unit during the study. However, these changes were not statistically significant (P > 0.05).

Conclusions

A high dose of vitamin D can improve the NIHSS score and decrease IL-1 and IL-6, although these changes were not statistically significant. The mean NLR and PLR decreased after using high-dose vitamin D.

Stroke-heart syndrome: A case report and mini literature review

Despite the fact that cardiac troponin (cTn) elevation is commonly seen in the acute phase of ischemic stroke, investigating its etiology represents a challenge for healthcare practitioners. Therefore, we describe the case of an 86-year-old woman with dyspnea and cTn-elevation within the first days following acute ischemic stroke and discuss potential differential diagnoses and diagnostic dilemmas.

The role of circulating cell-free DNA as an inflammatory mediator after stroke

Stroke is the second leading cause of death worldwide and a leading cause of disability. Clinical and experimental studies highlighted the complex role of the immune system in the pathophysiology of stroke. Ischemic brain injury leads to the release of cell-free DNA, a damage-associated molecular pattern, which binds to pattern recognition receptors on immune cells such as toll-like receptors and cytosolic inflammasome sensors. The downstream signaling cascade then induces a rapid inflammatory response. In this review, we are highlighting the characteristics of cell-free DNA and how these can affect a local as well as a systemic response after stroke. For this purpose, we screened literature on clinical studies investigating cell-free DNA concentration and properties after brain ischemia. We report the current understanding for mechanisms of DNA uptake and sensing in the context of post-stroke inflammation. Moreover, we compare possible treatment options targeting cell-free DNA, DNA-sensing pathways, and the downstream mediators. Finally, we describe clinical implications of this inflammatory pathway for stroke patients, open questions, and potential future research directions.

Systemic innate myeloid responses to acute ischaemic and haemorrhagic stroke

Acute ischaemic and haemorrhagic stroke account for significant disability and morbidity burdens worldwide. The myeloid arm of the peripheral innate immune system is critical in the immunological response to acute ischaemic and haemorrhagic stroke. Neutrophils, monocytes, and dendritic cells (DC) contribute to the evolution of pathogenic local and systemic inflammation, whilst maintaining a critical role in ongoing immunity protecting against secondary infections. This review aims to summarise the key alterations to myeloid immunity in acute ischaemic stroke, intracerebral haemorrhage (ICH), and subarachnoid haemorrhage (SAH). By integrating clinical and preclinical research, we discover how myeloid immunity is affected across multiple organ systems including the brain, blood, bone marrow, spleen, and lung, and evaluate how these perturbations associate with real-world outcomes including infection. These findings are placed in the context of the rapidly developing field of human immunology, which offers a wealth of opportunity for further research.

Intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is a dramatic condition caused by the rupture of a cerebral vessel and the entry of blood into the brain parenchyma. ICH is a major contributor to stroke-related mortality and dependency: only half of patients survive for 1 year after ICH, and patients who survive have sequelae that affect their quality of life. The incidence of ICH has increased in the past few decades with shifts in the underlying vessel disease over time as vascular prevention has improved and use of antithrombotic agents has increased. The pathophysiology of ICH is complex and encompasses mechanical mass effect, haematoma expansion and secondary injury. Identifying the causes of ICH and predicting the vital and functional outcome of patients and their long-term vascular risk have improved in the past decade; however, no specific treatment is available for ICH. ICH remains a medical emergency, with prevention of haematoma expansion as the key therapeutic target. After discharge, secondary prevention and management of vascular risk factors in patients remains challenging and is based on an individual benefit-risk balance evaluation.

Heart-Brain Team Approach of Acute Myocardial Infarction Complicating Acute Stroke: Characteristics of Guideline-Recommended Coronary Revascularization and Antithrombotic Therapy and Cardiovascular and Bleeding Outcomes

Background Acute myocardial infarction (AMI) infrequently occurs after acute stroke. The Heart-brain team approach has a potential to appropriately manage this poststroke cardiovascular complication. However, clinical outcomes of AMI complicating acute stroke (AMI-CAS) with the heart-brain team approach have not been characterized. The current study investigated cardiovascular outcomes in patients with AMI-CAS managed by a heart-brain team. Methods and Results We retrospectively analyzed 2390 patients with AMI at our institute (January 1, 2007-September 30, 2020). AMI-CAS was defined as the occurrence of AMI within 14 days after acute stroke. Major adverse cerebral/cardiovascular events (cardiac-cause death, nonfatal myocardial infarction, and nonfatal stroke) and major bleeding events were compared in subjects with  AMI-CAS and those without acute stroke. AMI-CAS was identified in 1.6% of the subjects. Most AMI-CASs (37/39=94.9%) presented ischemic stroke. Median duration of AMI from the onset of acute stroke was 2 days. Patients with AMI-CAS less frequently received primary percutaneous coronary intervention (43.6% versus 84.7%; P<0.001) and dual-antiplatelet therapy (38.5% versus 85.7%; P<0.001), and 33.3% of them did not receive any antithrombotic agents (versus 1.3%; P<0.001). During the observational period (median, 2.4 years [interquartile range, 1.1-4.4 years]), patients with AMI-CAS exhibited a greater likelihood of experiencing major adverse cerebral/cardiovascular events (hazard ratio [HR], 3.47 [95% CI, 1.99-6.05]; P<0.001) and major bleeding events (HR, 3.30 [95% CI, 1.34-8.10]; P=0.009). These relationships still existed even after adjusting for clinical characteristics and medication use (major adverse cerebral/cardiovascular event: HR, 1.87 [95% CI, 1.02-3.42]; P=0.04; major bleeding: HR, 2.67 [95% CI, 1.03-6.93]; P=0.04). Conclusions Under the heart-brain team approach, AMI-CAS was still a challenging disease, reflected by less adoption of primary percutaneous coronary intervention and antithrombotic therapies, with substantially elevated cardiovascular and major bleeding risks. Our findings underscore the need for a further refined approach to mitigate their ischemic/bleeding risks.

Immune regulation based on sex differences in ischemic stroke pathology

Ischemic stroke is one of the world's leading causes of death and disability. It has been established that gender differences in stroke outcomes prevail, and the immune response after stroke is an important factor affecting patient outcomes. However, gender disparities lead to different immune metabolic tendencies closely related to immune regulation after stroke. The present review provides a comprehensive overview of the role and mechanism of immune regulation based on sex differences in ischemic stroke pathology.

The Heart Is at Risk: Understanding Stroke-Heart-Brain Interactions with Focus on Neurogenic Stress Cardiomyopathy-A Review

In recent years, it has been convincingly demonstrated that acute brain injury may cause severe cardiac complications-such as neurogenic stress cardiomyopathy (NSC), a specific form of takotsubo cardiomyopathy. The pathophysiology of these brain-heart interactions is complex and involves sympathetic hyperactivity, activation of the hypothalamic-pituitary-adrenal axis, as well as immune and inflammatory pathways. There have been great strides in our understanding of the axis from the brain to the heart in patients with isolated acute brain injury and more specifically in patients with stroke. On the other hand, in patients with NSC, research has mainly focused on hemodynamic dysfunction due to arrhythmias, regional wall motion abnormality, or left ventricular hypokinesia that leads to impaired cerebral perfusion pressure. Comparatively little is known about the underlying secondary and delayed cerebral complications. The aim of the present review is to describe the stroke-heart-brain axis and highlight the main pathophysiological mechanisms leading to secondary and delayed cerebral injury in patients with concurrent hemorrhagic or ischemic stroke and NSC as well as to identify further areas of research that could potentially improve outcomes in this specific patient population.

Worst spasticity in patients post-stroke associated with MNSOD ALA16VAL polymorphism and interleukin-1β

The MnSOD Ala16Val single nucleotide polymorphism (SNP) has shown to be associated to risk factors of several metabolic and vascular diseases. However, little is known about interaction between MnSOD Ala16Val SNP in stroke, a frequent neurologic disease that involves clinic manifestations such as motor deficits and spasticity. In this sense, we decided to investigate the relationship between MnSOD Ala16Val SNP with spasticity in stroke and also its influence on interleukin levels, BDNF, and glycolipid parameters. Eighty post-stroke subjects and 80 healthy controls were investigated. We showed a higher spasticity, levels of total cholesterol, LDL, IL-1β, IL-6, and INF-γ in VV post-stroke group. Interesting, we found a correlation between IL-1β levels and spasticity in VV post-stroke. Triglycerides, glucose levels and caspases (1 and 3) activation were significantly higher, as well as BDNF levels were lower in VV and AV post-stroke. DNA damage was higher in post-stroke group. Thus, we can suggest that the V allele has a worse glycolipid profile, which would facilitate changes in neurovascular homeostasis. These events associated with an increase in inflammatory markers and a reduction in BDNF can contribute with the stroke and a worse clinical evolution in relation to spasticity in patients with VV genotype.

Regulatory Effect of JAK2/STAT3 on the Immune Function of Endotoxin-tolerant Dendritic Cells and its Involvement in Acute Liver Failure

BACKGROUND AND AIMS

Acute liver failure (ALF) is a potentially fatal clinical syndrome with no effective treatment. This study aimed to explore the role of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway in modulating the phenotype and immune function of endotoxin-tolerant dendritic cells (ETDCs). In addition, we explored the use of EDTCs in an experimental model of ALF and investigated the associated mechanisms.

METHODS

In the in vitro experiment, ETDCs were transfected with adenovirus to induce SOCS1^+/+ETDCs and SOCS1^-/-ETDCs. Thereafter, costimulatory molecules and mixed lymphocyte reaction were assessed. Experimental mice were randomly divided into normal control, ALF, ALF+mock-ETDCs, ALF+SOCS1^+/+ETDCs, ALF+AG490, and ALF+AG490+SOCS1^+/+ETDCs groups. We examined the therapeutic effect of adoptive cellular immunotherapy by tail-vein injection of target ETDCs 12 h before ALF modeling. AG490, a JAK2/STAT3 inhibitor, was used in the in vivo experiment to further explore the protective mechanism of SOCS1^+/+ETDCs.

RESULTS

Compared with control ETDCs, SOCS1^+/+ETDCs had lower expression of costimulatory molecules, weaker allostimulatory ability, lower levels of IL-6 and TNF-α expression and higher IL-10 secretion. SOCS1^-/-ETDCs showed the opposite results. In the in vivo experiments, the ALF+SOCS1^+/+ETDCs and ALF+AG490+SOCS1^+/+ETDCs groups showed less pathological damage and suppressed activation of JAK2/STAT3 pathway. The changes were more pronounced in the ALF+AG490+SOCS1^+/+ETDCs group. Infusion of SOCS1^+/+ETDCs had a protective effect against ALF possibly via inhibition of JAK2 and STAT3 phosphorylation.

CONCLUSIONS

The SOCS1 gene had an important role in induction of endotoxin tolerance. SOCS1^+/+ETDCs alleviated lipopolysaccharide/D-galactosamine-induced ALF by downregulating the JAK2/STAT3 signaling pathway.

Dissecting Polygenic Etiology of Ischemic Stroke in the Era of Precision Medicine

Ischemic stroke (IS), the leading cause of death and disability worldwide, is caused by many modifiable and non-modifiable risk factors. This complex disease is also known for its multiple etiologies with moderate heritability. Polygenic risk scores (PRSs), which have been used to establish a common genetic basis for IS, may contribute to IS risk stratification for disease/outcome prediction and personalized management. Statistical modeling and machine learning algorithms have contributed significantly to this field. For instance, multiple algorithms have been successfully applied to PRS construction and integration of genetic and non-genetic features for outcome prediction to aid in risk stratification for personalized management and prevention measures. PRS derived from variants with effect size estimated based on the summary statistics of a specific subtype shows a stronger association with the matched subtype. The disruption of the extracellular matrix and amyloidosis account for the pathogenesis of cerebral small vessel disease (CSVD). Pathway-specific PRS analyses confirm known and identify novel etiologies related to IS. Some of these specific PRSs (e.g., derived from endothelial cell apoptosis pathway) individually contribute to post-IS mortality and, together with clinical risk factors, better predict post-IS mortality. In this review, we summarize the genetic basis of IS, emphasizing the application of methodologies and algorithms used to construct PRSs and integrate genetics into risk models.

Signaling pathways involved in ischemic stroke: molecular mechanisms and therapeutic interventions

Ischemic stroke is caused primarily by an interruption in cerebral blood flow, which induces severe neural injuries, and is one of the leading causes of death and disability worldwide. Thus, it is of great necessity to further detailly elucidate the mechanisms of ischemic stroke and find out new therapies against the disease. In recent years, efforts have been made to understand the pathophysiology of ischemic stroke, including cellular excitotoxicity, oxidative stress, cell death processes, and neuroinflammation. In the meantime, a plethora of signaling pathways, either detrimental or neuroprotective, are also highly involved in the forementioned pathophysiology. These pathways are closely intertwined and form a complex signaling network. Also, these signaling pathways reveal therapeutic potential, as targeting these signaling pathways could possibly serve as therapeutic approaches against ischemic stroke. In this review, we describe the signaling pathways involved in ischemic stroke and categorize them based on the pathophysiological processes they participate in. Therapeutic approaches targeting these signaling pathways, which are associated with the pathophysiology mentioned above, are also discussed. Meanwhile, clinical trials regarding ischemic stroke, which potentially target the pathophysiology and the signaling pathways involved, are summarized in details. Conclusively, this review elucidated potential molecular mechanisms and related signaling pathways underlying ischemic stroke, and summarize the therapeutic approaches targeted various pathophysiology, with particular reference to clinical trials and future prospects for treating ischemic stroke.

Targeted BRD4 protein degradation by dBET1 ameliorates acute ischemic brain injury and improves functional outcomes associated with reduced neuroinflammation and oxidative stress and preservation of blood-brain barrier integrity

Bromodomain-containing protein 4 (BRD4), a member of the bromodomain and extra-terminal domain (BET) protein family, plays a crucial role in regulating inflammation and oxidative stress that are tightly related to stroke development and progression. Consequently, BRD4 blockade has attracted increasing interest for associated neurological diseases, including stroke. dBET1 is a novel and effective BRD4 degrader through the proteolysis-targeting chimera (PROTAC) strategy. We hypothesized that dBET1 protects against brain damage and neurological deficits in a transient focal ischemic stroke mouse model by reducing inflammation and oxidative stress and preserving the blood–brain barrier (BBB) integrity. Post-ischemic dBET1 treatment starting 4 h after stroke onset significantly ameliorated severe neurological deficits and reduced infarct volume 48 h after stroke. dBET1 markedly reduced inflammation and oxidative stress after stroke, indicated by multiple pro-inflammatory cytokines and chemokines including IL-1β, IL-6, TNF-α, CCL2, CXCL1 and CXCL10, and oxidative damage markers 4-hydroxynonenal (4-HNE) and gp91^phox and antioxidative proteins SOD2 and GPx1. Meanwhile, stroke-induced BBB disruption, increased MMP-9 levels, neutrophil infiltration, and increased ICAM-1 were significantly attenuated by dBET1 treatment. Post-ischemic dBET1 administration also attenuated ischemia-induced reactive gliosis in microglia and astrocytes. Overall, these findings demonstrate that BRD4 degradation by dBET1 improves acute stroke outcomes, which is associated with reduced neuroinflammation and oxidative stress and preservation of BBB integrity. This study identifies a novel role of BET proteins in the mechanisms resulting in ischemic brain damage, which can be leveraged to develop novel therapies.

Analgecine protects against cerebral ischemia-reperfusion through apoptosis inhibition and anti-neuroinflammation in rats

Stroke influence the quality of life of patients and leave big public health issues as acute cerebrovascular disease all over the world. Analgecine (AGC) relieves pain and accelerates repair of nerve injury. This current study aims to observe the pharmacological effects and related mechanisms of AGC in cerebral ischemic stroke among middle cerebral artery ischemia-reperfusion (MCAO) rats. After seven days of AGC administration, motor function was enhanced as evidenced by the prehensile traction test. Morphological ameliorations were observed by immunohistochemistry analysis. The protein expression levels of HSP70, Bcl-2, Bax, TRAF-6, MyD88, BDNF, NGF, pCREB, CREB, pTrkB, TrkB, pAKT and AKT were estimated by western blot. Meanwhile, AGC alleviated MCAO-induced inflammation chiefly by decreasing inflammatory cytokines in rat brain tissues. These results above suggested that MCAO-caused brain infarction was obviously alleviated by AGC. The immunohistochemistry data showed that AGC reduced neuronal injury and apoptosis, and inhibited microglia and astrocytes activation. The protein results suggested the expression of apoptosis-relevant proteins decreased among AGC treated groups and the neurotrophin related proteins were obviously enhanced by CREB/BDNF/TrkB/AKT and HSP70/Bcl-2/Bax pathways. Collectively, the results demonstrated that AGC primarily promoted neuro-nutrition, reduced the injury of nerve apoptosis and ameliorated neuroinflammation. In summary, AGC played a neuroprotective role, which had provided reliable evidence for AGC to be a potential drug in treating stroke.

Neuroinflammation, Stroke, Blood-Brain Barrier Dysfunction, and Imaging Modalities

Maintaining blood-brain barrier (BBB) integrity is crucial for the homeostasis of the central nervous system. Structurally comprising the BBB, brain endothelial cells interact with pericytes, astrocytes, neurons, microglia, and perivascular macrophages in the neurovascular unit. Brain ischemia unleashes a profound neuroinflammatory response to remove the damaged tissue and prepare the brain for repair. However, the intense neuroinflammation occurring during the acute phase of stroke is associated with BBB breakdown, neuronal injury, and worse neurological outcomes. Here, we critically discuss the role of neuroinflammation in ischemic stroke pathology, focusing on the BBB and the interactions between central nervous system and peripheral immune responses. We highlight inflammation-driven injury mechanisms in stroke, including oxidative stress, increased MMP (matrix metalloproteinase) production, microglial activation, and infiltration of peripheral immune cells into the ischemic tissue. We provide an updated overview of imaging techniques for in vivo detection of BBB permeability, leukocyte infiltration, microglial activation, and upregulation of cell adhesion molecules following ischemic brain injury. We discuss the possibility of clinical implementation of imaging modalities to assess stroke-associated neuroinflammation with the potential to provide image-guided diagnosis and treatment. We summarize the results from several clinical studies evaluating the efficacy of anti-inflammatory interventions in stroke. Although convincing preclinical evidence suggests that neuroinflammation is a promising target for ischemic stroke, thus far, translating these results into the clinical setting has proved difficult. Due to the dual role of inflammation in the progression of ischemic damage, more research is needed to mechanistically understand when the neuroinflammatory response begins the transition from injury to repair. This could have important implications for ischemic stroke treatment by informing time- and context-specific therapeutic interventions.

Caspase-1: A Promising Target for Preserving Blood–Brain Barrier Integrity in Acute Stroke

The blood–brain barrier (BBB) acts as a physical and biochemical barrier that plays a fundamental role in regulating the blood-to-brain influx of endogenous and exogenous components and maintaining the homeostatic microenvironment of the central nervous system (CNS). Acute stroke leads to BBB disruption, blood substances extravasation into the brain parenchyma, and the consequence of brain edema formation with neurological impairment afterward. Caspase-1, one of the evolutionary conserved families of cysteine proteases, which is upregulated in acute stroke, mainly mediates pyroptosis and compromises BBB integrity via lytic cellular death and inflammatory cytokines release. Nowadays, targeting caspase-1 has been proven to be effective in decreasing the occurrence of hemorrhagic transformation (HT) and in attenuating brain edema and secondary damages during acute stroke. However, the underlying interactions among caspase-1, BBB, and stroke still remain ill-defined. Hence, in this review, we are concerned about the roles of caspase-1 activation and its associated mechanisms in stroke-induced BBB damage, aiming at providing insights into the significance of caspase-1 inhibition on stroke treatment in the near future.

Interleukins and Ischemic Stroke

Ischemic stroke after cerebral artery occlusion is one of the major causes of chronic disability worldwide. Interleukins (ILs) play a bidirectional role in ischemic stroke through information transmission, activation and regulation of immune cells, mediating the activation, multiplication and differentiation of T and B cells and in the inflammatory reaction. Crosstalk between different ILs in different immune cells also impact the outcome of ischemic stroke. This overview is aimed to roughly discuss the multiple roles of ILs after ischemic stroke. The roles of IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-12, IL-13, IL-15, IL-16, IL-17, IL-18, IL-19, IL-21, IL-22, IL-23, IL-32, IL-33, IL-34, IL-37, and IL-38 in ischemic stroke were discussed in this review.

Quantitative Analysis of Stress-Induced Hyperglycemia and Intracranial Blood Volumes for Predicting Mortality After Intracerebral Hemorrhage

Stress-induced hyperglycemia (SIH) is a neuroendocrine response to acute illness. Although SIH has an adverse association with intracerebral hemorrhage (ICH), quantitative measures and determinants of SIH are not well delineated. In the present study, we objectively evaluated SIH using glycemic gap (GG) and identified its radiological and clinical determinants, with a 5-year retrospective review of charts of ICH patients. We calculated GG using the regression equation (GG = AG -28.7 × HbA1c + 46.7) and evaluated whether GG is an independent predictor of mortality using a multivariate regression model. Radiological volumes of different intracranial compartments were determined using image segmentation software. We correlated GG with different clinical and radiological parameters using Pearson correlation coefficient (PCC), Spearman's rank correlation (SRC), and Wilcoxon rank sum test. Then, we calculated the value of GG associated with mortality. Out of 328 patients, 238 (73%) survived hospitalization and 90 (27%) expired. GG was found to be an independent predictor of mortality (r=0.008, p=0.04). Additionally, GG was positively correlated with intraparenchymal hemorrhage (IPH) volume (PCC=0.185, p<0.01) and intraventricular hemorrhage (IVH) volume (PCC=0.233, p<0.01) and negatively correlated with cerebrospinal fluid (CSF) volume (PCC=-0.151, p<0.01) and brain tissue volume (PCC=-0.099, p=0.08). GG was positively correlated with patients' ICH score (SRC=0.377, p<0.01), Glasgow Coma Scale (GCS) (PCC=-0.356, p<0.01), hydrocephalus (p<0.01), and IVH in the third ventricle (p<0.01). The univariate logistic regression model identified 30.0 mg/dl as the value of GG (AUC=0.655, p<0.01) that predicted mortality with 52.2% sensitivity and 75.2% specificity and defined SIH. In conclusion, GG independently predicts mortality in ICH patients and positively correlates with IPH and IVH volumes. However, causality between the two is not established and would require specifically designed studies.

Single-center experience using anakinra for steroid-refractory immune effector cell-associated neurotoxicity syndrome (ICANS)

In addition to remarkable antitumor activity, chimeric antigen receptor (CAR) T-cell therapy is associated with acute toxicities such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Current treatment guidelines for CRS and ICANS include use of tocilizumab, a monoclonal antibody that blocks the interleukin (IL)-6 receptor, and corticosteroids. In patients with refractory CRS, use of several other agents as third-line therapy (including siltuximab, ruxolitinib, anakinra, dasatinib, and cyclophosphamide) has been reported on an anecdotal basis. At our institution, anakinra has become the standard treatment for the management of steroid-refractory ICANS with or without CRS, based on recent animal data demonstrating the role of IL-1 in the pathogenesis of ICANS/CRS. Here, we retrospectively analyzed clinical and laboratory parameters, including serum cytokines, in 14 patients at our center treated with anakinra for steroid-refractory ICANS with or without CRS after standard treatment with tisagenlecleucel (Kymriah) or axicabtagene ciloleucel (Yescarta) CD19-targeting CAR T. We observed statistically significant and rapid reductions in fever, inflammatory cytokines, and biomarkers associated with ICANS/CRS after anakinra treatment. With three daily subcutaneous doses, anakinra did not have a clear, clinically dramatic effect on neurotoxicity, and its use did not result in rapid tapering of corticosteroids; although neutropenia and thrombocytopenia were common at the time of anakinra dosing, there were no clear delays in hematopoietic recovery or infections that were directly attributable to anakinra. Anakinra may be useful adjunct to steroids and tocilizumab in the management of CRS and/or steroid-refractory ICANs resulting from CAR T-cell therapies, but prospective studies are needed to determine its efficacy in these settings.

Lithium promotes recovery after spinal cord injury

Lithium is associated with oxidative stress and apoptosis, but the mechanism by which lithium protects against spinal cord injury remains poorly understood. In this study, we found that intraperitoneal administration of lithium chloride (LiCl) in a rat model of spinal cord injury alleviated pathological spinal cord injury and inhibited expression of tumor necrosis factor α, interleukin-6, and interleukin 1 β. Lithium inhibited pyroptosis and reduced inflammation by inhibiting Caspase-1 expression, reducing the oxidative stress response, and inhibiting activation of the Nod-like receptor protein 3 inflammasome. We also investigated the neuroprotective effects of lithium intervention on oxygen/glucose-deprived PC12 cells. We found that lithium reduced inflammation, oxidative damage, apoptosis, and necrosis and up-regulated nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 in PC12 cells. All-trans retinoic acid, an Nrf2 inhibitor, reversed the effects of lithium. These results suggest that lithium exerts anti-inflammatory, anti-oxidant, and anti-pyroptotic effects through the Nrf2/heme oxygenase-1 pathway to promote recovery after spinal cord injury. This study was approved by the Animal Ethics Committee of Xi’an Jiaotong University (approval No. 2018-2053) on October 23, 2018.

Evolution of Blood-Brain Barrier Permeability in Subacute Ischemic Stroke and Associations With Serum Biomarkers and Functional Outcome

Background and Purpose: In the setting of acute ischemic stroke, increased blood-brain barrier permeability (BBBP) as a sign of injury is believed to be associated with increased risk of poor outcome. Pre-clinical studies show that selected serum biomarkers including C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNFα), matrix metallopeptidases (MMP), and vascular endothelial growth factors (VEGFs) may play a role in BBBP post-stroke. In the subacute phase of stroke, increased BBBP may also be caused by regenerative mechanisms such as vascular remodeling and therefore may improve functional recovery. Our aim was to investigate the evolution of BBBP in ischemic stroke using contrast-enhanced (CE) magnetic resonance imaging (MRI) and to analyze potential associations with blood-derived biomarkers as well as functional recovery in subacute ischemic stroke patients.

Methods: This is an exploratory analysis of subacute ischemic stroke patients enrolled in the BAPTISe study nested within the randomized controlled PHYS-STROKE trial (interventions: 4 weeks of aerobic fitness training vs. relaxation). Patients with at least one CE-MRI before (v1) or after (v2) the intervention were eligible for this analysis. The prevalence of increased BBBP was visually assessed on T1-weighted MR-images based on extent of contrast-agent enhancement within the ischemic lesion. The intensity of increased BBBP was assessed semi-quantitatively by normalizing the mean voxel intensity within the region of interest (ROI) to the contralateral hemisphere (“normalized CE-ROI”). Selected serum biomarkers (high-sensitive CRP, IL-6, TNF-α, MMP-9, and VEGF) at v1 (before intervention) were analyzed as continuous and dichotomized variables defined by laboratory cut-off levels. Functional outcome was assessed at 6 months after stroke using the modified Rankin Scale (mRS).

Results: Ninety-three patients with a median baseline NIHSS of 9 [IQR 6–12] were included into the analysis. The median time to v1 MRI was 30 days [IQR 18–37], and the median lesion volume on v1 MRI was 4 ml [IQR 1.2–23.4]. Seventy patients (80%) had increased BBBP visible on v1 MRI. After the trial intervention, increased BBBP was still detectable in 52 patients (74%) on v2 MRI. The median time to v2 MRI was 56 days [IQR 46–67]. The presence of increased BBBP on v1 MRI was associated with larger lesion volumes and more severe strokes. Aerobic fitness training did not influence the increase of BBBP evaluated at v2. In linear mixed models, the time from stroke onset to MRI was inversely associated with normalized CE-ROI (coefficient −0.002, Standard Error 0.007, p < 0.01). Selected serum biomarkers were not associated with the presence or evolution of increased BBBP. Multivariable regression analysis did not identify the occurrence or evolution of increased BBBP as an independent predictor of favorable functional outcome post-stroke.

Conclusion: In patients with moderate-to-severe subacute stroke, three out of four patients demonstrated increased BBB permeability, which decreased over time. The presence of increased BBBP was associated with larger lesion volumes and more severe strokes. We could not detect an association between selected serum biomarkers of inflammation and an increased BBBP in this cohort. No clear association with favorable functional outcome was observed.

Trial registration: NCT01954797.

Clinical Utility of Serum Holotranscobalamin Measurements in Patients with First-Ever Ischemic Stroke

Background

Whether holotranscobalamin (holoTC) indicates B12 deficiency more sensitively than total vitamin B12 (B12) is unclear. This study is aimed at determining the impact of serum holoTC level as a risk factor for ischemic stroke and investigating its association with disease severity and short-term outcomes.

Methods

Serum holoTC, total B12, and homocysteine levels were compared between 130 stroke patients and 138 healthy controls. Biomarker level correlations with disease severity and stroke functional outcomes were investigated.

Results

holoTC levels were lower and homocysteine levels were higher in stroke patients than in healthy controls (P < 0.05). The holoTC/total B12 ratio and homocysteine level significantly predicted ischemic stroke in the multivariable regression analysis (P < 0.05). Along with hyperhomocysteinemia, patients more often had holoTC than total B12 deficiency (6.2% vs. 3.1%). holoTC levels negatively correlated with homocysteine levels (partial R -0.165, P < 0.05) in stroke patients in multiple linear regression analyses, but not total B12 levels. The holoTC level and holoTC/total B12 ratio, but not homocysteine and total B12 levels, negatively correlated with the National Institute of Health Stroke Scale (partial R, -0.405 and -0.207, respectively, P < 0.01).

Conclusions

Measurements of serum holoTC levels combined with total B12 and homocysteine levels may provide valuable information for predicting ischemic stroke and its severity and short-term outcomes of ischemic stroke patients.

Brain Immune Interactions-Novel Emerging Options to Treat Acute Ischemic Brain Injury

Ischemic stroke is still among the leading causes of mortality and morbidity worldwide. Despite intensive advancements in medical sciences, the clinical options to treat ischemic stroke are limited to thrombectomy and thrombolysis using tissue plasminogen activator within a narrow time window after stroke. Current state of the art knowledge reveals the critical role of local and systemic inflammation after stroke that can be triggered by interactions taking place at the brain and immune system interface. Here, we discuss different cellular and molecular mechanisms through which brain–immune interactions can take place. Moreover, we discuss the evidence how the brain influence immune system through the release of brain derived antigens, damage-associated molecular patterns (DAMPs), cytokines, chemokines, upregulated adhesion molecules, through infiltration, activation and polarization of immune cells in the CNS. Furthermore, the emerging concept of stemness-induced cellular immunity in the context of neurodevelopment and brain disease, focusing on ischemic implications, is discussed. Finally, we discuss current evidence on brain–immune system interaction through the autonomic nervous system after ischemic stroke. All of these mechanisms represent potential pharmacological targets and promising future research directions for clinically relevant discoveries.

Interleukin-1 receptor inhibition reduces stroke size in a murine model of sickle cell disease

Sickle cell disease (SCD) is associated with chronic hemolytic anemia and a heightened inflammatory state. The causal role of inflammatory pathways in stroke associated with SCD is unclear. Therefore, the hypothesis that deletion of the non-hematopoietic interleukin-1 receptor (IL-1R) pool may be beneficial in SCD was pursued. Since potential deleterious effects of IL-1R signaling in SCD could be mediated via downstream production of interleukin-6 (IL-6), the role of the nonhematopoietic IL-6 pool was also addressed. Bone marrow transplantation (BMT) from SCD to wild-type (WT) recipient mice was used to generate SCD mice (Wt,SCDbmt). In order to generate mice with nonhematopoietic deficiency of IL-1R or IL-6, SCD marrow was transplanted into IL-1R deficient (IL1R-/-,SCDbmt) or IL-6 deficient recipients (IL6-/-, SCDbmt). Blood counts, reticulocytes, soluble E-selectin (sEsel), and IL-6 levels were analyzed 14-15 weeks post-BMT. Ischemic stroke was induced by middle cerebral artery (MCA) photothrombosis at 16 weeks post-BMT. A separate group of Wt,SCDbmt mice was given the IL-1R inhibitor, anakinra, following stroke induction. Seventy-two hours after MCA occlusion, stroke volume was assessed by staining brain sections with 2,3,5-triphenyltetrazolium chloride. Formalin-fixed brain sections were also stained for macrophages with MAC3, for endothelial activation with ICAM-1, and for loss of blood brain barrier integrity with fibrin (ogen) staining. All SCD mice generated by BMT were anemic and the severity of anemia was not different between Wt,SCDbmt, IL1R-/-,SCDbmt, and IL-6-/-,SCDbmt mice. Three days following MCA occlusion, stroke volume was significantly reduced in IL1R-/-,SCDbmt mice compared to Wt,SCDbmt mice and IL6-/-,SCDbmt mice. Plasma levels of sEsel were lower in IL1R-/-,SCDbmt compared to Wt,SCDbmt and IL-6-/-,SCDbmt mice. Post-stroke treatment of Wt,SCDbmt mice with anakinra decreased stroke size, leukocyte infiltration, ICAM-1 expression, and fibrin(ogen) accumulation compared to vehicle-treated mice. Deficiency of non-hematopoietic IL-1R or treatment with an IL-1R antagonist is sufficient to confer protection against the increased stroke size associated with SCD. These effects of IL1R deficiency are associated with reduced endothelial activation, leukocyte infiltration, and blood brain barrier disruption, and are independent of non-hematopoietic IL-6 signaling.

Modulating poststroke inflammatory mechanisms: Novel aspects of mesenchymal stem cells, extracellular vesicles and microglia

Inflammation plays an important role in the pathological process of ischemic stroke, and systemic inflammation affects patient prognosis. As resident immune cells in the brain, microglia are significantly involved in immune defense and tissue repair under various pathological conditions, including cerebral ischemia. Although the differentiation of M1 and M2 microglia is certainly oversimplified, changing the activation state of microglia appears to be an intriguing therapeutic strategy for cerebral ischemia. Recent evidence indicates that both mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (EVs) regulate inflammation and modify tissue repair under preclinical stroke conditions. However, the precise mechanisms of these signaling pathways, especially in the context of the mutual interaction between MSCs or MSC-derived EVs and resident microglia, have not been sufficiently unveiled. Hence, this review summarizes the state-of-the-art knowledge on MSC- and MSC-EV-mediated regulation of microglial activity under ischemic stroke conditions with respect to various signaling pathways, including cytokines, neurotrophic factors, transcription factors, and microRNAs.

Association of early glycemic change with short-term mortality in lobar and non-lobar intracerebral hemorrhage

The association between early glycemic change and short-term mortality in non-diabetic patients with acute intracerebral hemorrhage (ICH) is unclear. We retrospectively investigated non-diabetic patients with lobar (n = 262) and non-lobar ICH (n = 370). Each patient had a random serum glucose test on hospital admission and a fasting serum glucose test within the following 48 h. Hyperglycemia was defined as serum glucose ≥ 7.8 mmol/l. Four patterns were determined: no hyperglycemia (reference category), persistent hyperglycemia, delayed hyperglycemia, and decreasing hyperglycemia. Associations with 30-day mortality were estimated using Cox models adjusted for major features of ICH severity. Persistent hyperglycemia was associated with 30-day mortality in both lobar (HR 3.00; 95% CI 1.28–7.02) and non-lobar ICH (HR 4.95; 95% CI 2.20–11.09). In lobar ICH, 30-day mortality was also associated with delayed (HR 4.10; 95% CI 1.77–9.49) and decreasing hyperglycemia (HR 2.01, 95% CI 1.09–3.70). These findings were confirmed in Cox models using glycemic change (fasting minus random serum glucose) as a continuous variable. Our study shows that, in non-diabetic patients with ICH, early persistent hyperglycemia is an independent predictor of short-term mortality regardless of hematoma location. Moreover, in non-diabetic patients with lobar ICH, both a positive and a negative glycemic change are associated with short-term mortality.

Cytokine-Laden Extracellular Vesicles Predict Patient Prognosis after Cerebrovascular Accident

Background: A major contributor to disability after hemorrhagic stroke is secondary brain damage induced by the inflammatory response. Following stroke, global increases in numerous cytokines—many associated with worse outcomes—occur within the brain, cerebrospinal fluid, and peripheral blood. Extracellular vesicles (EVs) may traffic inflammatory cytokines from damaged tissue within the brain, as well as peripheral sources, across the blood–brain barrier, and they may be a critical component of post-stroke neuroinflammatory signaling. Methods: We performed a comprehensive analysis of cytokine concentrations bound to plasma EV surfaces and/or sequestered within the vesicles themselves. These concentrations were correlated to patient acute neurological condition by the Glasgow Coma Scale (GCS) and to chronic, long-term outcome via the Glasgow Outcome Scale-Extended (GOS-E). Results: Pro-inflammatory cytokines detected from plasma EVs were correlated to worse outcomes in hemorrhagic stroke patients. Anti-inflammatory cytokines detected within EVs were still correlated to poor outcomes despite their putative neuroprotective properties. Inflammatory cytokines macrophage-derived chemokine (MDC/CCL2), colony stimulating factor 1 (CSF1), interleukin 7 (IL7), and monokine induced by gamma interferon (MIG/CXCL9) were significantly correlated to both negative GCS and GOS-E when bound to plasma EV membranes. Conclusions: These findings correlate plasma-derived EV cytokine content with detrimental outcomes after stroke, highlighting the potential for EVs to provide cytokines with a means of long-range delivery of inflammatory signals that perpetuate neuroinflammation after stroke, thus hindering recovery.

Engineering 3D Cortical Spheroids for an In Vitro Ischemic Stroke Model

Three-dimensional (3D) spheroids composed of brain cells have shown great potential to mimic the pathophysiology of the brain. However, a 3D spheroidal brain-disease model for cerebral ischemia has not been reported. This study investigated an ultralow attachment (ULA) surface-mediated formation of 3D cortical spheroids using primary rat cortical cells to recapitulate the cerebral ischemic responses in stroke by oxygen-glucose deprivation-reoxygenation (OGD-R) treatment. Comparison between two-dimensional (2D) and 3D cell culture models confirmed the better performance of the 3D cortical spheroids as normal brain models. The cortical cells cultured in 3D maintained their healthy physiological morphology of a less activated state and suppressed mRNA expressions of pathological stroke markers, S100B, IL-1β, and MBP, selected based on in vivo stroke model. Interestingly, the spheroids formed on the ULA surface exhibited striking aggregation dynamics involving active cell-substrate interactions, whereas those formed on the agarose surface aggregated passively by the convective flow of the media. Accordingly, ULA spheroids manifested a layered arrangement of neurons and astrocytes with higher expressions of integrin β1, integrin α5, N-cadherin, and fibronectin than the agarose spheroids. OGD-R-induced stroke model of the ULA spheroids successfully mimicked the ischemic response as evidenced by the upregulated mRNA expressions of the key markers for stroke, S100B, IL-1β, and MBP. Our study suggested that structurally and functionally distinct cortical spheroids could be generated by simply tuning the cell-substrate binding activities during dynamic spheroidal formation, which should be an essential factor to consider in establishing a brain-disease model.

Role of microglial and endothelial CD36 in post-ischemic inflammasome activation and interleukin-1β-induced endothelial activation

Cerebral ischemia is associated with an acute inflammatory response that contributes to the resulting injury. The innate immunity receptor CD36, expressed in microglia and endothelium, and the pro-inflammatory cytokine interleukin-1β (IL-1β) are involved in the mechanisms of ischemic injury. Since CD36 has been implicated in activation of the inflammasome, the main source of IL-1β, we investigated whether CD36 mediates brain injury through the inflammasome and IL-1β. We found that active caspase-1, a key inflammasome component, is decreased in microglia of CD36-deficient mice subjected to transient middle cerebral artery occlusion, an effect associated with a reduction in brain IL-1β. Conditional deletion of CD36 either in microglia or endothelium reduced ischemic injury in mice, attesting to the pathogenic involvement of CD36 in both cell types. Application of an ischemic brain extract to primary brain endothelial cell cultures from wild type (WT) mice induced IL-1β-dependent endothelial activation, reflected by increases in the cytokine colony stimulating factor-3, a response markedly attenuated in CD36-deficient endothelia. Similarly, the increase in colony stimulating factor-3 induced by recombinant IL-1β was attenuated in CD36-deficient compared to WT endothelia. We conclude that microglial CD36 is a key determinant of post-ischemic IL-1β production by regulating caspase-1 activity, whereas endothelial CD36 is required for the full expression of the endothelial activation induced by IL-1β. The data identify microglial and endothelial CD36 as critical upstream components of the acute inflammatory response to cerebral ischemia and viable putative therapeutic targets.

Pathophysiologic mechanisms of cerebral endotheliopathy and stroke due to Sars-CoV-2

Cerebrovascular events have emerged as a central feature of the clinical syndrome associated with Sars-CoV-2 infection. This increase in infection-related strokes is marked by atypical presentations including stroke in younger patients and a high rate of hemorrhagic transformation after ischemia. A variety of pathogenic mechanisms may underlie this connection. Efforts to identify synergism in the pathophysiology underlying stroke and Sars-CoV-2 infection can inform the understanding of both conditions in novel ways. In this review, the molecular cascades connected to Sars-CoV-2 infection are placed in the context of the cerebral vasculature and in relationship to pathways known to be associated with stroke. Cytokine-mediated promotion of systemic hypercoagulability is suggested while direct Sars-CoV-2 infection of cerebral endothelial cells may also contribute. Endotheliopathy resulting from direct Sars-CoV-2 infection of the cerebral vasculature can modulate ACE2/AT1R/MasR signaling pathways, trigger direct viral activation of the complement cascade, and activate feed-forward cytokine cascades that impact the blood-brain barrier. All of these pathways are already implicated as independent mechanisms driving stroke and cerebrovascular injury irrespective of Sars-CoV-2. Recognizing the overlap of molecular pathways triggered by Sars-CoV-2 infection with those implicated in the pathogenesis of stroke provides an opportunity to identify future therapeutics targeting both Sars-CoV-2 and stroke thereby reducing the impact of the global pandemic.

Targeting cardiovascular inflammation: next steps in clinical translation

Systemic vascular inflammation plays multiple maladaptive roles which contribute to the progression and destabilization of atherosclerotic cardiovascular disease (ASCVD). These roles include: (i) driving atheroprogression in the clinically stable phase of disease; (ii) inciting atheroma destabilization and precipitating acute coronary syndromes (ACS); and (iii) responding to cardiomyocyte necrosis in myocardial infarction (MI). Despite an evolving understanding of these biologic processes, successful clinical translation into effective therapies has proven challenging. Realizing the promise of targeting inflammation in the prevention and treatment of ASCVD will likely require more individualized approaches, as the degree of inflammation differs among cardiovascular patients. A large body of evidence has accumulated supporting the use of high-sensitivity C-reactive protein (hsCRP) as a clinical measure of inflammation. Appreciating the mechanistic diversity of ACS triggers and the kinetics of hsCRP in MI may resolve purported inconsistencies from prior observational studies. Future clinical trial designs incorporating hsCRP may hold promise to enable individualized approaches. The aim of this Clinical Review is to summarize the current understanding of how inflammation contributes to ASCVD progression, destabilization, and adverse clinical outcomes. We offer forward-looking perspective on what next steps may enable successful clinical translation into effective therapeutic approaches-enabling targeting the right patients with the right therapy at the right time-on the road to more individualized ASCVD care.

Targeting the gasdermin D as a strategy for ischemic stroke therapy

Stroke is a major cause of death and disability worldwide that triggers a variety of neuropathological conditions, leading to the initiation of several pro-inflammatory mediators and neuronal damage. Neuroinflammation has been considered the potential therapeutic target and contributes to the pathology of ischemia and reperfusion. Pyroptosis is an inflammatory form of programmed cell death that plays an important role in immune protection against stroke. Gasdermin D (GSDMD) is the final executor of pyroptosis upon cleavage by caspases-1/4/5/11, followed by canonical and noncanonical inflammasome activation, leading to a series of inflammatory responses. GSDMD N-terminal domain assembles plasma membrane as well as organelle membrane pores to induce cytolysis, thereby triggering cytokine release and inflammatory-related cell death. In our review, we concisely summarized and highlighted the potential role of GSDMD-regulated pyroptosis and the biological characteristic of GSDMD as a therapeutic target in ischemic stroke. A better understanding of the roles of GSDMD may provide a theoretical basis for the design of novel therapeutic interventions for the treatment of ischemic stroke.

Cytokines as therapeutic targets for cardio- and cerebrovascular diseases

Despite major advances in prevention and treatment, cardiac and cerebral atherothrombotic complications still account for substantial morbidity and mortality worldwide. In this context, inflammation is involved in the chronic process leading atherosclerotic plaque formation and its complications, as well as in the maladaptive response to acute ischemic events. For this reason, modulation of inflammation is nowadays seen as a promising therapeutic strategy to counteract the burden of cardio- and cerebrovascular disease. Being produced and recognized by both inflammatory and vascular cells, the complex network of cytokines holds key functions in the crosstalk of these two systems and orchestrates the progression of atherothrombosis. By binding to membrane receptors, these soluble mediators trigger specific intracellular signaling pathways eventually leading to the activation of transcription factors and a deep modulation of cell function. Both stimulatory and inhibitory cytokines have been described and progressively reported as markers of disease or interesting therapeutic targets in the cardiovascular field. Nevertheless, cytokine inhibition is burdened by harmful side effects that will most likely prevent its chronic use in favor of acute administrations in well-selected subjects at high risk. Here, we summarize the current state of knowledge regarding the modulatory role of cytokines on atherosclerosis, myocardial infarction, and stroke. Then, we discuss evidence from clinical trials specifically targeting cytokines and the potential implication of these advances into daily clinical practice.

Association of Serum IL-6 (Interleukin 6) With Functional Outcome After Intracerebral Hemorrhage

BACKGROUND AND OBJECTIVES

IL-6 (interleukin 6) is a proinflammatory cytokine and an established biomarker in acute brain injury. We sought to determine whether admission IL-6 levels are associated with severity and functional outcome after spontaneous intracerebral hemorrhage (ICH).

METHODS

We performed an exploratory analysis of the recombinant activated FAST trial (Factor VII for Acute ICH). Patients with admission serum IL-6 levels were included. Regression analyses were used to assess the associations between IL-6 and 90-day modified Rankin Scale. In secondary analyses, we used linear regression to evaluate the association between IL-6 and baseline ICH and perihematomal edema volumes.

RESULTS

Of 841 enrolled patients, we included 552 (66%) with available admission IL-6 levels (mean age 64 [SD 13], female sex 203 [37%]). IL-6 was associated with poor outcome (modified Rankin Scale, 4-6; per additional 1 ng/L, odds ratio, 1.30 [95% CI, 1.04-1.63]; P=0.02) after adjustment for known predictors of outcome after ICH and treatment group. IL-6 was associated with ICH volume after adjustment for age, sex, and ICH location, and this association was modified by location (multivariable interaction, P=0.002), with a stronger association seen in lobar (β, 12.51 [95% CI, 6.47-18.55], P<0.001) versus nonlobar (β 5.32 [95% CI, 3.36-7.28], P<0.001) location. IL-6 was associated with perihematomal edema volume after adjustment for age, sex, ICH volume, and ICH location (β 1.22 [95% CI, 0.15-2.29], P=0.03). Treatment group was not associated with IL-6 levels or outcome.

CONCLUSIONS

In the FAST trial population, higher admission IL-6 levels were associated with worse 90-day functional outcome and larger ICH and perihematomal edema volumes.

Post-Stroke Cardiovascular Complications and Neurogenic Cardiac Injury: JACC State-of-the-Art Review

Over 1.5 million deaths worldwide are caused by neurocardiogenic syndromes. Furthermore, the consequences of deleterious brain-heart interactions are not limited to fatal complications. Cardiac arrhythmias, heart failure, and nonfatal coronary syndromes are also common. The brain-heart axis is implicated in post-stroke cardiovascular complications known as the stroke-heart syndrome, sudden cardiac death, and Takotsubo syndrome, among other neurocardiogenic syndromes. Multiple pathophysiological mechanisms with the potential to be targeted with novel therapies have been identified in the last decade. In the present state-of-the-art review, we describe recent advances in the understanding of anatomical and functional aspects of the brain-heart axis, cardiovascular complications after stroke, and a comprehensive pathophysiological model of stroke-induced cardiac injury.